well im not sure what all you already have in there but i would start with some hardy ones. clowns, damsels, and chromis look good and are very hardy. foxface rabbit fish do well also. I added a foxface and a golden headed sleeper goby just 4 days after moving into the 125 gallon tank and they are doing great. once you add a few and you see that they are doing well then you can go with something a little different. angel fish and maybe a few tangs. they say that you should only have one type of tang but in my expierence i have found that as long as you add the different kinds of tangs in at the same time then they do just fine together, and they will make the tank look fuller since they are very active swimmers.